\begin{tikzpicture}[>=Stealth]
    \clip (0.05, 0.9) rectangle (3.95, -5.95);
    \draw (0, 0) -- (4, 0);
    \fill [pattern = dots] (0, 0) rectangle (4, -6);

    \filldraw [pattern = bricks] (0.05, 0) rectangle (0.85, 0.375) node [pos=0.5, above=0.5em] {$A$};

    \filldraw [fill=white] (0, -1.97) rectangle (2, -2.67);
    \filldraw [fill=white] (1.2, 0) -- (1.2, -4.86) --  (4, -4.86) -- (4, -4.16) -- (2.0, -4.16) -- (2.0, 0)  -- cycle;
    \fill [fill=white] (0, -1.97) rectangle (2, -2.67);

    \node at (1.2, -2.3) {$B$};
    \node at (2.1, -4.5) {$C$};
\end{tikzpicture}
